• Title/Summary/Keyword: 확산 이론

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Immersed Boundary Method for numerical Analysis of Bridge Section (가상경계법을 이용한 교량 내풍단면 유동장 수치해석)

  • Kim, Hak Sun;Lee, Sungsu;Nho, Jae Geun
    • 한국방재학회:학술대회논문집
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    • 2011.02a
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    • pp.69-69
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    • 2011
  • 본 논문에서는 비정상 상태의 비압축성 유동장을 해석하기 위하여 물체맞춤격자방법이 아닌 가상경계법을 사용하였다. 가상경계법은 구조격자를 사용하여 구조물 경계면에서 Momentum Forceing을 사용하여 가상의 경계를 만들어 유동장을 해석하는 방법이다. Navier-Stoke 방정식의 수치 이산화 방법으로 Kim et al(1985)이 사용한 Fractional Step Method(FSM)을 사용하였다. 시간에 대하여 semi-implicit FSM를 사용하였고, 확산항에 대해서는 2차 정확도의 Crank-Nicolson Method를 대류항은 3차 정확도의 Runge-Kutta Method를 사용 하였다. 본 연구에서는 가상경계법을 이용한 유동장 해석이 교량 단면에 대하여 수치해석이 가능한지 검토하였다. 가상경계법은 현재 많은 연구가 유선형의 구조물에 대하여 수행되어 오고 있다. 교량 단면과 같은 각 진 구조물에 대한 검토는 아직 미비한 실정이다. 가상경계법에서 다루고 있는 구조물 경계면에서의 Momentum Forcing 방법이 유선형의 구조물에 맞추어 연구가 진행되었기 때문이다. 먼저 본 연구의 프로그램을 검증하기 위하여 원형 실린더에 대하여 가상경계법을 적용한 결과 Re 수 200에서 Strouhal Number, 양력계수, 항력계수를 이전 연구 결과와 비교하였다. Williamson(1988)과 Zhang(1995)의 연구결과와 유사한 결과를 얻을 수 있다. 그리고 교량의 단면과 같은 각진 구조물(Bluff Body)에 대하여 가상경계법 적용하였다. 본 논문의 연구에서 평가 대상으로 하고 있는 2차원 교량 단면에 대하여 유동장 해석을 하였다. 본 논문에서 정량적인 유체력과 유동장에 대한 비교 및 검토가 이루어지지 못했지만 압력장과 유선의 형태가 이론적인 값을 벗어나지 않고 있는 것으로 확인 되었다. Re 수 2700에서 전산 해석을 수행하였으며, 교량 단면 주위의 압력계수와 박리현상 그리고 후류에서의 Vortex shedding 현상이 모두 적절한 분포가 나타나는 것을 확인할 수 있었다. 따라서 가상경계법을 이용하여 각진 구조물에 대한 주위 유동장해석에 대한 가능성을 확인하였으며, 풍동실험과의 결과비교를 통하여 가상경계법을 이용하여 교량 단면 주위의 유동장 해석 결과를 정량적으로 비교할 것이다.

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A study on the electron ionization and attachment coefficients ins $SF_6$ gas ($SF_6$ 가스의 전리 및 부착계수에 관한 연구)

  • Seo, Sang-Hyeon;Yu, Heoi-Young;Kim, Sang-Nam;Ha, Sung-Chul
    • The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.10 no.6
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    • pp.96-103
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    • 1996
  • This paper describes the electron transport characteristics in SF6 gas calculated for range of E/N values from 150~ 800[Td) by the Monte Carlo simulation and Boltzmann equation method using a set of electron collision cross sections detennined by the authors and the values of electron swarm parameters are obtained by TOF method. The results gRined that the values of the electron swarm parameters such as the electron drift velocity, the electron ionization or Rttachment coefficients, longitudinal and transverse diffusion coefficients agree with the experimental and theoretical for a range of E/N. The properties of electron avalanches is concerned electron energy non--equilibrium region. The electron energy distributions function were analysed in sulphur hexafluoride at E/N : 500~800[Td) for a case of non-equilibrium region in the mean electron energy. The validity of the results obtained has been confilll1ed by a TOF method.

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Effects of Innovation Characteristics and User Characteristics on the Adopting e-Books : Focused on Innovation Resistance Model (혁신특성과 사용자특성이 전자책 수용에 미치는 영향 : 혁신저항모형을 중심으로)

  • Yoon, Su-Kyung;Kim, Myeong-Ji;Choi, Jun-Ho
    • The Journal of the Korea Contents Association
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    • v.14 no.8
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    • pp.61-73
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    • 2014
  • While past studies on e-books have mainly focused on the uses and gratifications (UG) and technology acceptance model(TAM), this study rather analysed the innovation resistance factors of adopting the e-book based on the innovation resistance model. The research model comprises of two factors: 1) innovation characteristics which include relative advantages, compatability and complexity, 2) user characteristics which encompass attitudes towards innovation and existing products (i.e., paper books). Using online survey questionnaire, this study examined the effects of those innovation and user characteristics on the innovation resistance, and the relationship between innovation resistance and intention of adoption. The results showed that complexity and attitude towards existing products affected the innovation resistance which has negative influence on the intention of adoption. Accordingly, it is necessary to improve the ease of use in the whole process from purchase to reading experiences, and highlight e-books' own interactive features and functions which are perceived as different from paper-book user experience.

A Study of On/Off-line Trust on Customer's Repurchase Intention in Hotel Industry (온/오프라인 호텔기업의 신뢰와 고객의 재구매의도에 관한 연구)

  • Min, Bo-Young
    • The Journal of the Korea Contents Association
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    • v.9 no.8
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    • pp.412-422
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    • 2009
  • With the development of the Internet, online community has been made possible to buy a product in hotel industry. It is expanded gradually the customers buy various banquet services as well as guest rooms or restaurant use. From the 1950s, research has been conducted on trust and various study is achieved in connection with in social psychology or industry marketing. But there is much to be desired on research on trust in on/off-line company and customer's repurchase intention. Verifying the study model and hypothesis established through proceeding research, we would like to know that whether trust in on-line basis can be connected with the trust that already formed about the hotel in off-line basis. Furthermore, how on-line and off-line trust made in hotel industry can affects to customer's repurchase intention. The trust between on-line basis and off-line basis in hotel industry is mutually related. The trust based on off-line hotel company also affects to customer's repurchase intention. But, on-line trust in hotel industry is not related to the customer's repurchase intention.

The Status Quo of Humanities-Based Museum Education Program (박물관에서의 인문학 연계 교육을 위한 현황 분석)

  • kang, Inae;Seol, Yeon-Kyung;Lee, Sohyun
    • The Journal of the Korea Contents Association
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    • v.15 no.8
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    • pp.611-624
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    • 2015
  • Humanities-collaborated practices in various fields have been supported by several governmental policies as a way to overcome recent social problems. Museum, due to its roles in preserving and sharing cultural and historical heritage for the development of society and communities, has emerged as a key base for the humanities-collaborated practices. This study, in this context, aimed to analyze how the humanities-based museum education programs have been practiced in the museums, which, in turn, might provide a basic data for the future direction and development of the programs and the related governmental policy as well. For this purpose, this study first examined theoretical framework for the link between humanities and museum education, from which a survey was developed. The survey was conducted to 75 museum educators who have been in charge of humanities-based educational programs. The result showed that most programs seemed to reflect the basic direction and purpose of the humanities-linked with museum education. Yet, more needs were found in terms of the educational themes and methods which can facilitate multicultural literacy and reflective thinking and activities within experiential learning environments.

Factors Affecting Technology Transfer of Government-funded Research Institutes (정부출연연구기관 기술이전 영향요인에 관한 연구)

  • Yun, Jang-ho
    • Journal of Korea Technology Innovation Society
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    • v.20 no.3
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    • pp.519-545
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    • 2017
  • This study analyzed the factors influencing the technology transfer of Government-Funded Research Institutes from the perspective of resource-based view. In particular, we analyzed the effects of research resources, research capacity, and research results diffusion variables on technology transfer performance. The research resource variables affect the primary output of R&D (patents, research papers) but direct effect on the technology transfer performance was very weak. Among the research competency variables, patent-related variables such as patent registration, patent holdings have a significant effect on the technology transfer performance. However, the research papers have a negative effect on the technology transfer performance. The research results diffusion variables such as TLO organization and TLO budget may partly have a positive impact on technology transfer, but the statistical significance is not clear.

Effects of Brand Self-Disclosure and User Social Connectedness on Response to Facebook Brand Fan Pages (페이스북 브랜드 팬 페이지에 대한 이용자의 반응 -브랜드의 자기노출정도와 이용자의 사회적 연결감을 중심으로-)

  • Lee, Eunsun;Kim, Yeo Jung;Ahn, Jungsun
    • The Journal of the Korea Contents Association
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    • v.13 no.8
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    • pp.60-71
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    • 2013
  • The current study examines the major variables -Facebook social connectedness and brand self-disclosure- that affect the relationship between users and brands. In this study, we assume that users communicate and build relationships with brands via Facebook brand fan pages, like they do with other users. Additionally, we test the effect of attitude toward Facebook fan page on intention to be a fan of the fan page. The results show that the brand's self-disclosure positively affects on attitude toward the fan page, but Facebook social connectedness has negative effects. Also, attitude toward the fan page has positive effects on the intention to be a fan. This study helps understand how brand messages are spreading across diverse Facebook users.

A Comparative Study on Service Quality and Consumer Behavior of Social Network Service between Korea and China (소셜네트워크 서비스(SNS) 서비스 품질과 사용자 선택행동에 대한 한·중비교 연구)

  • Fan, Qing-Ji;Kim, Won-Kyum
    • The Journal of the Korea Contents Association
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    • v.14 no.12
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    • pp.950-958
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    • 2014
  • According to the rapid spreading of smart phone, the use of social network service(SNS) is also increasing rapidly. Social network service(SNS) which plays an important role in customer relationship management and brand management is becoming more important. This study aims to find out if differences exist in the perceptions of service quality and the consumer behaviors between Korean and Chinese consumers using SNS. In order to achieve the objectives of the study, the literatures of service quality and consumer behavior theory is reviewed. And based on the literature reviews, dimensions related to service quality and consumer behavior are derived and T-test is used to identify the differences. According to the analysis, significant differences exist in the perceptions of service quality and consumer behaviors between Korean and Chinese consumers using SNS. The results not only provide theoretical evidences for further SNS study but also provide practical evidences for companies in their overseas expansion.

Consumption Attribute Value Estimation of Digital Music Contents Service by Conjoint Analysis (컨조인트 분석을 통한 디지털 음악콘텐츠 서비스의 소비 속성별 가치 추정)

  • Shin, Dong-Myoung;Kim, Bo-Young
    • The Journal of the Korea Contents Association
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    • v.14 no.12
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    • pp.924-934
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    • 2014
  • In the last 10 years the digital music contents market has grown rapidly. However digital music contents product and services are not managed with product planning and price policy considered customer attitude and digital music contents values. This study is to define the value properties of digital music contents services based on streaming and download as genre, price, sound quality, and usage appliance, and suggest the strategic market price and service composition of digital music contents service by customer attitudes about the value properties. The research used the conjoint analysis methodology based on the hedonic price model and collected 405 questionaries by users of Korean digital music contents services to the analysis. Hence 'sound quality' in download platform, and 'appliance' in streaming platform were the elements to evaluate the customer attitude. The results present the music contents productions and companies have to provide the differentiated services and price by the value properties of user preference in the market.

Cryptanalysis using Fault Injection and Countermeasures on DSA (오류주입을 이용한 DSA 서명 알고리즘 공격 및 대응책)

  • Jung, Chul-Jo;Oh, Doo-Hwan;Choi, Doo-Sik;Kim, Hwan-Koo;Ha, Jae-Cheol
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.8
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    • pp.3045-3052
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    • 2010
  • The international standard signature algorithm DSA has been guaranteed its security based on discrete logarithm problem. Recently, the DSA was known to be vulnerable to some fault analysis attacks in which the secret key stored inside of the device can be extracted by occurring some faults when the device performs signature algorithm. After analyzing an existing fault attack presented by Bao et al., this paper proposed a new fault analysis attack by disturbing the random number. Furthermore, we presented a countermeasure to compute DSA signature that has its immunity in the two types of fault attacks. The security and efficiency of the proposed countermeasure were verified by computer simulations.